Which of these is the best win by these heavies?

I voted

1) Ali over Foreman
2) Holyfield over Tyson
3) Frazier over Ali

Number 1 is easy.

2 - almost everyone had Mike but Evander stood up to him and backed him down.

3 - Both undefeated and a great win for Frazier, little too early to take this fight in the Ali comeback for me, nonetheless a great win.

Foreman was a stylistic nightmare for Frazier and he smashed him accordingly.